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Various ecosystems of the Gulf of Mexico (GoM) may be impacted by the present increase in offshore oil exploitation. To identify future changes caused by this activity, we assessed the structure of the megabenthos community in the Perdido Fold Belt (PFB) and its relationships with environmental variables, hydrocarbons, and heavy metals. To achieve this, biological and sediment samples were obtained during the surveys Perdido II (PII) and Perdido III (PIII). 325.75 103 ind km−2 and 582.34 kg AFDW km−2 were collected, distributed in 110 species. Crustaceans and echinoderms comprised more than 70% of the total abundance and biomass. The most abundant species were Astropecten cingulatus Sladen, 1883, Callinectes sapidus Rathbun, 1896, Astropecten duplicatus Gray, 1840, and Penaeus aztecus (Ives, 1891) (12.2 103 ≤ ind Km−2 ≤ 59.4 103). They also had the greatest biomass contribution (16.8 ≤ kg AFDW km−2 ≤ 192.2). BIOENV test showed the influence of depth (Z), salinity, dissolved oxygen (DO), Acenaphthylene (Acy), Fluoranthene (Flu), n-C12, n-C37, and nickel (Ni) on the community structure. Recruitment and trawling also influenced the abundance and biomass values. Despite Z defines the environmental gradient, the hydrocarbon concentration gradient within the shelf areas makes it a good candidate for developing monitoring programmes. [ABSTRACT FROM AUTHOR]

Surface water samples from the Yucatan shelf presented Cd concentrations similar to those reported internationally for non-polluted coastal and marine waters. V concentrations, on the other hand, fall within the range of anthropogenically polluted waters (25% of the sampling sites). In the study area, the probable sources of V could be: (1) carbonate sediments leaching V into the water column and co-transported with fine sediments resuspending as a result of the complex hydrodynamics in the area or, (2) accidental spills from cargo ships transporting oil between the Atlantic and the Gulf of Mexico. Significant spatial and temporal differences were found for both metals; therefore, a regional interval concentration is suggested for V from 1.28 to 1.84 μg L−1 and Cd from 0.003 to 0.09 μg L−1. These differences could primarily be the result of the observed hydrology and hydrodynamics created by the Yucatan current, submarine groundwater discharges and upwelling. [ABSTRACT FROM AUTHOR]

Surface water samples from the Perdido study area presented Cd and V concentrations similar to those reported internationally for waters with: (1) fossil fuel extraction, processing and burning, and (2) sites polluted by anthropogenic wastewater. Results showed an order of magnitude increase in time for Cd, therefore, no general average value was established. For V, however, results of this study suggest a general average value of 1.4 µg L−1 for the area. The observed spatial variation of concentrations could be the result of: (1) temporal variation of external inputs to the area, and coincide with previously reported hydrodynamic patterns of dispersion related to significant river contributions and accumulation areas indicative of eddy circulation or fronts. The Perdido area showed Cd and V concentrations in surface water reflective of anthropogenic impacts, while its spatial and temporal variation could depend significantly on the hydrodynamics of the area. [ABSTRACT FROM AUTHOR]

This study analyzed 27 surface sediment samples from the Tamaulipas Continental shelf to determine the spatial–temporal distribution of V and Cd (spring–summer 2016; summer 2017). Average V concentrations (99 ± 18 mg g−1) were similar to that previously reported values for the area, while average Cd concentrations reflect uncontaminated sediments at surface level of the shelf. Inputs of V and Cd may be related to hydrocarbon and anthropogenic contributions from South and North of the Gulf of Mexico. The variability shown by both elements results from the hydrodynamics and hydrology of the area produced by local currents, eddies of the Loop Current, resuspension of fine sediments and contribution of terrigenous material. Considering that both metals showed significant differences (Shapiro–Wilk, p = 0), baseline concentrations could not be established, instead a reference interval of 79–122 µg g−1 for V and 0.121–0.258 µg g−1 for Cd in sediments from the Tamaulipas platform is suggested. [ABSTRACT FROM AUTHOR]

We investigated the spatial and temporal distribution of V and Cd in surface sediments of the Yucatan Shelf to establish current average values for the area. V and Cd concentrations are similar to those reported internationally for limestone rocks and surface marine sediments. The observed variability of V concentrations between cruises may be the result of changes in ocean current direction in summer (SW-S) and strong prevailing winds in autumn (N-NE). In addition to the hydrodynamics described above, Cd variations may also be associated with inputs of particulate material by upwelling events and subsequent transport and distribution to the shelf by the Yucatan Channel current (autumn). Considering that both metals showed significant spatial and temporal differences, a range of values for V (0.4–1.5 µg g−1) and Cd (0.05–0.2 µg g−1) are proposed as baseline reference for sediments of the Yucatan Shelf. [ABSTRACT FROM AUTHOR]

The present study evaluates the endocrine effect in flatfish through vitellogenin (vtg) gene expression and its association with pollutants data obtained from fish muscle and sediment from two regions in the Gulf of Mexico (GoM): Perdido Fold Belt (northwestern) and the Yucatan Peninsula (southeast). The results revealed induction of vtg in male flatfish in both geographical regions with different levels and patterns of distribution per oceanographic campaign (OC). In the Perdido Fold Belt, vtg was observed in male fish during four OC (carried out in 2016 and 2017), positively associated with Pb, V, Cd and bile metabolites (hydroxynaphthalene and hydroxyphenanthrene). In the Yucatan Peninsula, the induction of vtg in males was also detected in three OC (carried out in 2016 and 2018) mainly associated with Ni, Pb, Al, Cd, V and polycyclic aromatic hydrocarbons. Ultimately, estrogenic alterations could affect reproductive capacity of male flatfish in the GoM., (© 2023. The Author(s), under exclusive licence to Springer Science+Business Media, LLC, part of Springer Nature.)

In this study, the genotoxic effect of contaminants was assessed through detection of DNA damage using the micronucleus (MNs) test in erythrocytes from 149 flounder fish collected in two regions of the Gulf of Mexico (GoM). The frequency of microcytes (MCs) was also evaluated in the same group of fish collected from the Perdido Foldbelt (PF) and the Yucatan Platform (YP). The MCs frequency was different among locations of the YP (p = 0.011), while MNs frequency varied among locations of PF (p = 0.024). MCs and MNs values correlated with heavy metals from fish muscle, fish species and localities. Mean number, prevalence, and intensity of MCs and MNs correlated with Al, PAHs, depth, and locality. MNs frequency showed a species-specific association (p = 0.004). MNs and MCs were associated with heavy metals and PAHs from fish muscle and sediments, and the MNs frequency was species dependent., (© 2021. The Author(s), under exclusive licence to Springer Science+Business Media, LLC, part of Springer Nature.)

Oiling scenarios following spills vary in concentration and usually can affect large coastal areas. Consequently, this research evaluated different crude oil concentrations (10, 40, and 80 mg L -1 ) on the nearshore phytoplanktonic community in the southern Gulf of Mexico. This experiment was carried out for ten days using eight units of 2500 L each; factors monitored included shifts in phytoplankton composition, physicochemical parameters and the culturable bacterial abundance of heterotrophic and hydrocarbonoclastic groups. The temperature, salinity, and nutrient concentrations measured were within the ranges previously reported for Yucatan Peninsula waters. The total hydrocarbon concentration (TPH) in the control at T0 indicated the presence of hydrocarbons (PAHs 0.80 μg L -1 , aliphatics 7.83 μg L -1 and UCM 184.09 μg L -1 ). At T0, the phytoplankton community showed a similar assemblage structure and composition in all treatments. At T10, the community composition remained heterogeneous in the control, in agreement with previous reports for the area. However, for oiled treatments, Bacillariophyceae dominated at T10. Hydrocarbonoclastic bacteria were associated with oiled treatments throughout the experiment, while heterotrophic bacteria were associated with control conditions. Our results agreed with previous works at the taxonomic level showing the presence of Bacillariophyceae and Dinophyceae in oil-related treatments, where these groups showed the major interactions in co-occurrence networks. In contrast, Chlorophyceae showed the key node in the co-occurrence network for the control. This study aims to contribute to knowledge on phytoplankton community shifts during a crude oil spill in subtropical oligotrophic regions., (© 2021. The Author(s), under exclusive licence to Springer Science+Business Media, LLC, part of Springer Nature.)

Crude oil is one of the most widespread pollutants released into the marine environment, and native species have provided useful information about the effect of crude oil pollution in marine ecosystems. We consider that the lined sole Achirus lineatus can be a useful monitor of the effect of crude oil in the Gulf of Mexico (GoM) because this flounder species has a wide distribution along the GoM, and its response to oil components is relevant. The objective of this study was to compare the transcriptomic changes in liver and gill of adults lined sole fish (Achirus lineatus) exposed to a sublethal acute concentration of water-accommodated fraction (WAF) of light crude oil for 48 h. RNA-Seq was performed to assess the transcriptional changes in both organs. A total of 1073 differentially expressed genes (DEGs) were detected in gills; 662 (61.69%) were upregulated, and 411 (38.30%) were downregulated whereas in liver, 515 DEGs; 306 (59.42%) were upregulated, and 209 (40.58%) were downregulated. Xenobiotic metabolism and redox metabolism, along with DNA repair mechanisms, were activated. The induction of hypoxia-regulated genes and the generalized regulation of multiple signaling pathways support the hypothesis that WAF exposition causes a hypoxia-like condition., (© 2021. The Author(s), under exclusive licence to Springer-Verlag GmbH, DE part of Springer Nature.)

This study investigates the community composition, structure, and abundance of sulfate-reducing microorganisms (SRM) in surficial sediments of the Northwestern Gulf of Mexico (NWGoM) along a bathymetric gradient. For these purposes, Illumina sequencing and quantitative PCR (qPCR) of the dissimilatory sulfite reductase gene beta subunit (dsrB gene) were performed. Bioinformatic analyses indicated that SRM community was predominantly composed by members of Proteobacteria and Firmicutes across all the samples. However, Actinobacteria, Thermodesulfobacteria, and Chlorobi were also detected. Phylogenetic analysis indicated that unassigned dsrB sequences were related to Deltaproteobacteria and Nitrospirota superclusters, Euryarchaeota, and to environmental clusters. PCoA ordination revealed that samples clustered in three different groups. PERMANOVA indicated that water depth, temperature, redox, and nickel and cadmium content were the main environmental drivers for the SRM communities in the studied sites. Alpha diversity and abundance of SRM were lower for deeper sites, suggesting decreasing sulfate reduction activity with respect to water depth. This study contributes with the understanding of distribution and composition of dsrAB-containing microorganisms involved in sulfur transformations that may contribute to the resilience and stability of the benthic microbial communities facing metal and hydrocarbon pollution in the NWGoM, a region of recent development for oil and gas drilling.

Shelf and deep-water soft-bottom macrofauna were explored in the western Gulf of Mexico in terms of species and functional trait assemblages. Their variation was analysed as functions of depth and time, and the relationship with sea-bottom environmental conditions was examined to disentangle their association with potential environmental drivers. Four consecutive cruises (two per year, at the end of the dry and rainy seasons) were performed during 2016-2017 at 27 fixed stations distributed from 42 to 3565 m depth. Changes in macrofauna composition were tested considering species and functional trait assemblages. Environmental variables associated with sediment features (i.e., grain structure, organic matter, pH, redox), oceanographic conditions (i.e., temperature, dissolved oxygen, particulate organic carbon flux) and potential contaminants (i.e., hydrocarbons and metals) were analysed to identify potential drivers that would shape the structure of macrofauna assemblages. The results suggest that the structures of both species and functional trait assemblages change according to depth and show temporal variation in composition at seasonal and interannual scales. The effect of temporal variation represented about 12% of total variation in the assemblages (11.4 for species and 12.5% for functional-traits). Different patterns of spatial and temporal variation between shelf and deep benthic communities were observed. Variation in species assemblages on the shelf were related to the variation in lead, polycyclic aromatic hydrocarbons and the fine sand ratio. In the deep benthos, particulate carbon flux showed high correlation with the spatial and temporal variation in species assemblage. In the deep benthos the changes in the species assemblage between the dry and the rainy seasons and the interannual variation were highly correlated with particulate organic carbon input in the area., (Copyright © 2020 Elsevier Ltd. All rights reserved.)

Exposure of marine fish to hydrocarbon compounds from crude oil can cause physiological and ecological alterations that can result in several cytotoxic, genotoxic, and teratogenic damages. One consequence of this exposure is the dysbiosis of the gut microbiota, where the normal bacterial composition is modified. Herein, we assessed the effect of the exposure to water accommodated fraction (WAF) of a light crude oil into the gut microbiota of a native species, the lined sole Achirus lineatus, a benthonic fish widely distributed in the Gulf of Mexico (GoM). We performed a chronic bioassay using two WAF concentrations (5 and 10% v/v), collecting lined sole entire gastrointestinal tracts for microbiota analyses at two timepoints, 14 and 28 days. Changes in the gut microbiota composition were determined by high throughput amplicon sequencing of the gene 16S rRNA. Diversity analyses showed that WAF exposure produced similar changes in the microbiota composition at both concentrations. Metagenomic functional prediction showed that these alterations could result in a shift in the gut redox status, towards a more anoxygenic environment. Enrichment of bacteria capable of use hydrocarbon as carbon source seems to be fast regardless time of exposure or WAF concentrations. Our results suggest that chronic WAF exposure can cause a dysbiosis in this benthic native species from the GoM., (Copyright © 2020 Elsevier Ltd. All rights reserved.)